What is an FeLV "carrier?"
In feline leukemia carriers, 30 percent of exposed cats, the immune system weakens the virus enough that it doesn't make the cats sick. The virus is present in a carrier cat's body, but the cat does not show FeLV symptoms. Because of the lack of symptoms, an owner of an FeLV carrier probably will not realize that the cat has the virus. Meanwhile, the carrier cat can infect other cats because the virus is contagious. Carrier cats also are more vulnerable to other germs because their immune systems are busy fighting FeLV.